Year Measure 1971 180.74186 1972 190.65968 1973 206.7025 1974 219.38387 1975 222.47339 1976 235.0247 1977 252.50163 1978 261.42237 1979 272.30254 1980 270.07419 1981 264.75944 1982 268.96017 1983 273.13693 1984 275.17458 1985 274.22048 1986 276.78618 1987 278.18057 1988 286.34799 1989 305.10654 1990 306.21936 1991 315.98463 1992 328.80422 1993 335.42227 1994 353.42851 1995 344.88931 1996 357.38174 1997 363.55092 1998 365.9284 1999 384.42271 2000 381.9412 2001 400.27771 2002 402.29842 2003 396.07975 2004 464.6798 2005 486.35762 2006 489.01078 2007 498.59711 2008 511.63377 2009 508.9912 2010 527.02438 2011 560.10935 2012 559.92777 2013 554.1448 2014 553.10396